?????STUN ????UDP????????????NAT??Simple Traversal of UDP over NAT???????????Э?飬?????IP?綽????NAT???????IP?綽????????????Э????NAT?????????ж?NAT??????????IP?綽???????? STUNЭ?飬????????????е?STUN??????????????????????STUN??????????????????NAT??????????????IP????????IP?綽??????????????SIP/SDP????е????IP?????????SIP?????RTP??y????????????????NAT????????????NAT???κ????á?
    STUN???????????NAT???????????????????????NAT?????????????????SOHO·????????????NAT????????????￡????STUN???????????STUNЭ?鯔?????????NAT????????·?????????NAT????????STUN??

    ?????????????????NAT????????????????????????????????????

    ??????????????STUN??????
http://bgp.potaroo.net/ietf/rfc-pdf/rfc3489.pdf
???????STUN???????????￡?
1????STUN Client????NAT???????С?
2????????????OLC??????STUN  Client???????λ???????????STUN Server.
3??STUN Server??STUN Client????STUN Messgae??????STUN Server???????RTP/RTCP??NAT???????????STUN Client????
4??????????????????????????STUN Client???????????????RTP/RTCP?????????????дOLC???STUN Client?????NAT??????????д??OLC?????С????磺STUN Client???192.168.1.4:40000??192.168.1.4:40001 ??STUN Server??;??????NAT???????????221.12.27.14??2000??221.12.27.14??2039;??????????????RTP/RTCP????40000??40001????OLC?е???滻?221.12.27.14??2000??221.12.27.14??2039??
5??????????????????????????221.12.27.14??2000??221.12.27.14??2039???NAT?????192.168.1.4:40000??192.168.1.4:40001???
??????????4??NAT????????????STUN???????в????
?? ???STUN Server????в?????????????????Full Cone?????NAT????????
?? ???STUN Server??????????????????????????STUN Server??????STUN Server??????????OLC???????????Restricted Cone NAT????????????
?? ???STUN Server???????????????????STUN Server??????????OLC????????????????????
OpenH323 ????class H323EndPoint/class H323_RTP_UDP/class RTP_UDP???????????STUN Client??????????????H323EndPoint ::SetSTUNServer(…)?????????Client????????STUN Client???????PWLIB?У?http://cvs.sourceforge.net/viewcvs.py/openh323/pwlib/src/ptclib/pstun.cxx
???OpenH323?????STUN Server?????????????????????STUN Server/Client??????OpenH323?в???????????￡?http://sourceforge.net/projects/stun/?????????
??http://sourceforge.net/projects/stun/????????PWLIB?б?????????????OpenH323???????STUN Server??